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A062919 "Reverse factorials": product of the digit reversals of the numbers 1 through n. 2
1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 362880, 3991680, 83825280, 2598583680, 106541930880, 5433638474880, 331451946967680, 23533088234705280, 1906180147011127680, 173462393378012618880 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

How many trailing zeros are there in a(n)?

LINKS

Harry J. Smith, Table of n, a(n) for n = 0..100

FORMULA

a(n) = Product_{k=1..n} A004086(k). - Michel Marcus, Jun 28 2018

EXAMPLE

a(11) = 3991680 = 1*2*3*4*5*6*7*8*9*R(10)*R(11) = 1*2*3*4*5*6*7*8*9*1*11.

MATHEMATICA

FoldList[Times, 1, Table[FromDigits[Reverse[IntegerDigits[n]]], {n, 20}]] (* Harvey P. Dale, Aug 20 2012 *)

PROG

(PARI) Rev(x)= { local(d); r=0; while (x>0, d=x-10*(x\10); x\=10; r=r*10 + d); return(r) } { for (n=0, 100, if (n, a*=Rev(n), a=1); write("b062919.txt", n, " ", a) ) } \\ Harry J. Smith, Aug 13 2009

CROSSREFS

Cf. A000142, A004086.

Sequence in context: A109834 A131451 A084012 * A319211 A276843 A273696

Adjacent sequences:  A062916 A062917 A062918 * A062920 A062921 A062922

KEYWORD

base,nonn,easy

AUTHOR

Amarnath Murthy, Jul 02 2001

EXTENSIONS

More terms from Lior Manor and Larry Reeves (larryr(AT)acm.org), Jul 05 2001

STATUS

approved

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Last modified April 21 22:12 EDT 2019. Contains 322328 sequences. (Running on oeis4.)